(1) Field of the Invention
The present invention relates to a cutter of packed bags for use when packing a constant amount of a charge continuously in bags made of cylindrical resin film.
(2) Description of the Prior Art
A conventional cutter of packed bags made of cylindrical resin film and its operating procedure will be described with reference to FIGS. 3(A), (B), (C) and (D).
Generally cylindrical film 1 packed with a charge 2 is sealed by a sealing device 4, 4 at a sealing position as shown in FIG. 3(A). To the film under the sealing position 6 is attached a packed bag 1a which has previously formed. To the cylindrical resin film above the sealing position 6 is supplied a charge 2 in a constant amount. A pair of squeezing rolls are arranged above a sealing device consisting of a pair of sealing members 4,4 and located at such a position as to permit the forming of a packed bag. As shown in FIG. 3(B), the squeezing rolls 3,3 are moved to approach each other to press and divide the cylindrical film 1 filled with the charge 2 in a length necessary for one packed bag. Next the squeezing rolls 3,3 are rotated in the direction of the arrow marks to push the packed bag 1b downward under the heat-sealing device 4,4. Then the heat-sealing device 4,4 is in a position shown by the dotted lines, and moves in the direction indicated by the arrow marks and seals the film 1 at the position of real lines after the packed bag has moved downward. On the other hand, a cutting device or a cutter made of a pair of members is arranged in a position opposite to the sealed portion 6 at the bottom end of the packed bag, and the pair of members move toward each other to cut off the previously formed packed bag at the sealing portion 6. Thereafter the squeezing rolls 3,3 and the members of the heat-sealing device 4,4 both are respectively separated from each other, and the charge 2 is supplied into the cylindrical film 1, the bag packing operation being performed continuously by the same procedure.
The problems described hereunder arise in the use of the packing machine described above.
In the handling of a hot charge, the sealed portion 6 may be torn apart due to insufficient cooling when a hot charge 2 flows into the film 1 in the steps FIGS. 3(A) and (D), causing loss of the charge and the film. Further, although in FIG. 3(C) the distance L.sub.2 between the squeezing rolls 3,3 and the sealing device 4 and the distance L.sub.1 between the sealing device 4 and the cutter 5 are arranged so as to permit cutting of the film at the sealed portion 6, the cutting could occur, however, at the position of the sealed portion 6, thereby causing loss of the charge 2 and the film 1 and contamination of the environment of the machine, leading to reduced working efficiency, because in the actual operation the length of each one of the packed bags 1a, 1b is not necessarily constant due to variation of conditions of charge, e.g. temperature etc., or the like.